Molten-Salt Electrochemical Deoxidation Synthesis of Platinum-Neodymium Nanoalloy Catalysts for Oxygen Reduction Reaction

Platinum-rare earth metal (Pt-RE) nanoalloys are regarded as a potential high performance oxygen reduction reaction (ORR) catalyst. However, wet chemical synthesis of the nanoalloys is a crucial challenge because of the extremely high oxygen affinity of RE elements and the significantly different standard reduction potentials between Pt and RE. Here, this paper presents a molten-salt electrochemical synthetic strategy for the compositional-controlled preparation of platinum-neodymium (Pt-Nd) nanoalloy catalysts. Carbon-supported platinum-neodymium (Pt_x Nd/C) nanoalloys, with distinct compositions of Pt₅ Nd and Pt₂ Nd, are obtained through molten-salt electrochemical deoxidation of platinum and neodymium oxide (Pt-Nd₂ O₃ ) precursors supported on carbon. The Pt_x Nd/C nanoalloys, especially the Pt₅ Nd/C exhibit a mass activity of 0.40 A mg^-1 _Pt and a specific activity of 1.41 mA cm^-2 _Pt at 0.9 V versus RHE, which are 3.1 and 7.1 times higher, respectively, than that of commercial Pt/C catalyst. More significantly, the Pt₅ Nd/C catalyst is remarkably stable after undergoing 20 000 accelerated durability cycles. Furthermore, the density-functional-theory (DFT) calculations confirm that the ORR catalytic performance of Pt_x Nd/C nanoalloys is enhanced by compressive strain effect of Pt overlayer, causing a suitable weakened binding energies of O^* $\Delta E_{O^{\ast }}$ and $\Delta E_{{\mathrm{OH}}^{\ast }}$ .